Unloader means for a reciprocating compressor



Oct. 30, 1962 A. J. NICHOLAS ETAL 3,061,175

UNL'OADER MEANS FOR A RECIPROCATING COMPRESSOR Filed May 25, 1959 Emil Am y/law A S 5. AMMM L T H wm w mN b w WM w R United States Patent p 3,061,176 UNLOADER MEANS FOR A RECIPROCATING COMPRESSOR Andrew J. Nicholas, Suflield, Conn., and David N. Shaw,

West Springfield, Mass, assignors to Worthington Corporation, Harrison, N..l., a corporation of Delaware Filed May 25, 1959, Ser. No. 815,737

8 Claims. (ill. 23030) This invention relates to reciprocating compressors and more particularly to unloader means for varying the capacity of such compressors.

While an unloader of the throttling type is shown it will be evident to one skilled in the art that the unloader contemplated herein can readily be converted to the type of unloader shown in application Serial No. 741,254 filed June 11, 1958, now abandoned, by Daniel H. Bobis, Henry Soumerai and Andrew I. Nicholas, by providing actuating means such as pins in association with the movable element at one end and the suction valve strip at the other respective end.

In the common type of compresser installation, the compressor supplies working fluid to a storage tank from whence the fluid passes to use. The fluid pressure and capacity within the tank varies in accordance with the demands of the compressor installation to thereby vary the required output of the compressor.

As is well known the unloading means associated with the compressor functions to regulate the fluid pressure and capacity in the storage tank within predetermined limits by loading and unloading the compressor of the installation. There are a number of unloading means employed in the art for this purpose which, together with the present invention, are rather generally based on the same fundamental conception. Thus, they have a movable means associated with an actuating arm or the like whereupon the movable means at predetermined times moves the actuating means to load or unload the compressor. Others include means to prevent the entry of system fluid into the compressor to be acted upon thereby. The last mentioned type is usually referred to as a throttling type unloader.

Within the broad limits just defined, there is much room for improvement in these unloading means for reciprocating compressors. From the practical standpoint many of the compressors employ unloading means which are complex, expensive to manufacture and of an operative relationship with the compressor which befuddles the individuals charged with the proper operation of the compressor installation.

The present invention overcomes many of the difliculties in prior types of unloaders by providing a compressor with means for varying the capacity thereof wherein the unloader is of relatively simple design including a movable element mounted about the cylinder to provide a fluid tight chamber therebetween. Means are associated with the fluid tight chamber and through the movable element whereby when desired the movable element can be actuated to either permit or prevent flow from the low side of the system to the cylinder.

Accordingly, it is an object of the present invention to provide an unloader means which has relatively few parts and hence can be manufactured at less cost, can be assembled outside of the compressor as a sub-assembly, easily installed without misalignment, is easily removed and disassembled when repairs become necessary and is fabricated with minimum moving, sealing parts.

It is a further object of this invention to actuate an annular element mounted about the cylinder to cut off communication between the low side of the system and the cylinder.

With these and other objects in view, as may appear 3,061,176 Patented Oct. 30, 1962 from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings showing the unloader means associated with a reciprocating compressor, and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

FIGURE 1 is a partial transverse section through a cylinder of the compressor embodying the unloader means contemplating by this invention.

FIGURE 2 is a fragmentary section of a portion of the unloader means shown in FIGURE 1 in closed position.

Referring now to the drawings more in detail, FIG- URE 1 shows a portion of a reciprocating compressor including the novel unloader means. The compressor generally designated 1 includes a casing 2 having a first partition 6 therein for dividing the compressor into a compression compartment 4 wherein system fluid is acted upon and a crankcase compartment 5, usually housing the driving components of the compressor. A second partition 6 is disposed in the compression portion of the compressor for dividing same into a suction manifold 7 and a discharge compartment 8. The compressor generally designated 1 includes a cylinder 9 in which a piston 10 operates. A discharge valve cage 11 is secured to the cylinder 9 by any well known means and is'provided with suction inlet chamber 12, which communicates with the suction manifold 7 and a discharge outlet in the discharge valve cage 11 communicating with the discharge chamber 8.

While FIGURE 1 illustrates only one cylinder it will be understood by those familiar with this art that the present arrangement may be used in single or multicylinder reciprocating compressors. One such application in multi-cylinder compressors may be realized from the teachings of the above mentioned application'Serial No. 741,254.

FIGURE 1 shows the cylinder 9 comprising an elongated cylindrical liner having a flange 13 disposed about its upper end. The outer edge of the flange in assembled position having a sliding fit with the opening 14 formed in the second partition 6. The lower end of the cylinder liner has a slip fit with the opening 15 in the first partition 3', of lesser diameter but in alignment with the opening 14 in the upper partition.

The upper or outer face of the flange is connected to a valve plate by any well known fashion as by threaded means as is described in the above application wherein the valve plate acts to support the cylinder liner in operative position.

A second flange like means or annular boss 20 having a groove 21 thereabout is fashioned as an integral portion of the cylinder liner and'about the outer substantially central peripheral portion thereof. The last mentioned means is adapted to coact with the unloader means contemplated by this invention as is hereinafter described.

The piston 10 is adapted for reciprocation in the cylinder 9 in conventional fashion by means of a piston rod 30 driven through the usual crankshaft and suitable prime mover (not shown). Provision of a plurality of circumferentially spaced suction inlet ports 16 inwardly of the flange 13 provides communication between the suction manifold 7 and the cylinder 9. As is well known fluid will flow through the ports to the'cylinder in accordance with the position of the annular suction valve strip 17 disposed in the valve chamber and held in position by suction valve springs 18 as is clearly shown in the drawings.

The discharge chamber 8 communicates with the cylinder through the usual valve and port arrangement formed in the discharge valve cage as is well known in the art.

In order to operate the compressor at substantially constant speed but at increments of its full capacity, means taking the form of a movable annular element 22 is disposed about the cylinder and in close clearance with boss 20 and in such fashion as to provide a chamber 23 therebetween. Seal means 24 and 25, shown as O-rings are disposed respectively in a groove 26 formed in element 22 and the groove 21 formed in boss 20 to coact with the linear and element 22 to confine fluid passed to chamber 23 therein.

The flange 13, which fits in the opening formed in the second partition 6 and in substance therefore may be a part of the second partition, forms a surface against which the annular movable element 22 will normally be held in abutment by resilient means 27 shown as springs. This abutting relationship as is clearly shown in FIG- URE 2 occurs in the area of the flange circumjacent the inlet openings 12a of the suction inlet chamber 12. Abutment of the annular movable element 22 is maintained by spring means 27 disposed in bores 28 formed in the bottom of the annular movable element. Particularly the springs are disposed so that at one end they abut the partition 3 and at the other end abut the bottom of the bore 28 to urge the movable element 22 into abutment with the second partition or flange.

During the stage of compressor operation when element 22 abuts the flange or partition circumjacent the inlet openings 12a as is shown in FIGURE 2, it functions to preclude passage of gas from the suction manifold 7 through the inlet openings 12a and the suction inlet chamber 12 to the cylinder 9.

The term circumjacent whose meaning as used here in will appear obvious from the drawings, indicates that the movable element which is annular in form will contact the flange or partition circumferentially and adjacent the point where the inlet openings 12a communicate with the suction manifold 7.

The movable element is guided and aligned during assembly of the various elements by a fluid connecting means 29 which is in communication with the fluid tight chamber 23 at one end and a source of fluid such as the lubrication system of the compressor at the other end.

When proper conditions occur or when desired, fluid such as oil is passed from the source (not shown) to the fluid tight chamber 23 to thereby actuate the movable element out of engagement with flange 13 and open communication between the suction manifold 7 and the cylinder 9 to permit flow of refrigerant to the cylinder which is compressed and then discharged out the discharge portion of the compressor to the discharge compartment 8 and from there to its intended use.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that they may be widely modified within the invention defined by the claims.

What is claimed is:

1. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition means in the compression portion of the compressor for dividing the same into a suction manifold and a discharge compartment, means forming a cylinder in the compression compartment of the compressor, a piston slidably disposed in the means forming a cylinder, a suction inlet for the means forming a cylinder in communication with the suction manifold, a discharge outlet for the means forming a cylinder in communication with the discharge compartment, suction and discharge valve means movably mounted on the suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising a movable element about said means forming a cylinder and movable to abut said second partition means circumjacent said suction inlet to cut off communication between the suction manifold and said suction inlet.

2. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition means in the compression portion of the compressor for dividing same into a suction manifold and a discharge compartment, a cylinder liner forming a cylinder therein disposed in the compression compartment of the compressor; a piston operatively disposed in the cylinder, a suction inlet for the cylinder and in communication with the suction compartment, a discharge outlet for the cylinder and in communication with the discharge compartment, suction and discharge valve means movably mounted on the suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising a movable element mounted about said cylinder liner, means on the cylinder liner coacting with said movable element to form a fluid pressure chamber therebetween, said movable element normally disposed to engage the second partition means circumjacent said suction inlet to cut off communication between the suction manifold and the suction inlet for the cylinder, and connector means operatively associated with the fluid pressure chamber through said movable means for supplying operating medium to said fluid pressure chamber whereby the movable element is actuated out of engagement with the second partition means to permit communication between the suction manifold and the cylinder through said suction inlet.

3. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition in the compression portion of the compressor for dividing same into a suction manifold and a discharge compartment, a cylinder liner forming a cylinder therein disposed in the compression compartment of the compressor; a piston slidably disposed in the cylinder, a suction inlet for the cylinder in communication with the suction manifold, a dis charge outlet for the cylinder and in communication with the discharge compartment, suction and discharge valve means movably mounted on the said suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising a movable element mounted circumjacent said cylinder liner between the first and second partitions and normally abutting the portion of said cylinder liner about the suction inlet to cut off communication between the suction manifold and the suction inlet for the cylinder, and means for actuating said movable element out of abutting relation with said portion of the cylinder liner to permit communication between the suction manifold and the suction inlet for the cylinder.

4. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition in the compression portion of the compressor for dividing same into a suction manifold and a discharge compartment, a cylinder liner forming a cylinder therein disposed in the compression compartment of the compressor, a piston fluid pressure chamber therebetween, said movable element normally abutting the portion of said cylinder liner about the suction inlet to cut off communication between the suction manifold and suction inlet for the cylinder, and connector means connected to said fluid pressure chamber through said movable element for supplying operating medium for said fluid chamber whereby said movable element is actuated out of abutment with said portion of the cylinder liner and communication is permitted between the suction manifold aud the suction inlet for the cylinder.

5. The unloader means claimed in claim 4 wherein resilient means are disposed in said movable element and in engagement with the first partition to normally hold the movable element in abutment with said portion of the cylinder liner.

6. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition in the compression portion of the compressor for dividing same into a suction manifold and a discharge compartment, a cylinder liner having a flange thereabout and forming a cylinder therein disposed in the compression compartment of the compressor, a piston slidably disposed in the cylinder, a suction inlet for the cylinder extending through said flange and in communication with the suction mani fold, a discharge outlet for the cylinder and in communication with the discharge compartment, suction and discharge valve means movably mounted on the suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising a movable annular element mounted circumjacent said cylinder liner between said first and second partitions and normally abutting the flange to cut off communication between the suction manifold and the suction inlet for the cylinder, and means for actuating said annular element out of engagement with said flange to permit communication between the suction manifold and the cylinder through said suction inlet.

7. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition in the compression portion of the compressor for dividing same into a suction manifold and a discharge compartment, a cylinder liner having a flange thereabout and forming a cylinder therein disposed in the compression compartment of the compressor, a piston slidably disposed in the cylinder, a suction inlet for the cylinder extending through said flange and in communication with the suction manifold, a discharge outlet for the cylinder and in communication with the discharge compartment, suction and discharge valve means movably mounted on the suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising a movable annular element mounted circumjacent said cylinder liner between said first and second partitions, an annular member on the cylinder liner coacting with said movable annular element to form a fluid pressure chamber therebetween, said movable annular element normally disposed in abutment with said flange to cut off communication between the suction manifold and the suction inlet for the cylinder, and connector means connected to said fluid pressure chamber through said movable annular element for supplying operating medium to said fluid pressure chamber whereby said movable annular element is moved out of abutment with said flange to provide communication between the suction manifold and the cylinder through said suction inlet.

8. The unloader means claimed in claim 7 wherein springs are disposed in said movable annular element having one end in abutment with the first partition to normally hold said movable annular element in abutment with said flange.

References Cited in the file of this patent UNITED STATES PATENTS 

